In long term evolution (LTE) Release 9 (R9), a core set of multimedia broadcast multicast services (MBMS) features and working mechanisms were specified to provide the MBMS services to the LTE wireless transmit/receive units (WTRUs). This core set enables the unidirectional point-to-multipoint transmission of multimedia contents, (e.g., public media or news service text, audio, sports or entertainment or television (TV) broadcast pictures or video), from a single source point to a multicast group of recipients in a multicast service area. In LTE R9, the multicast service is provided in a mixed cell environment.
A mixed MBMS cell supports both the regular unicast operations (regular WTRU service) as well as the MBMS operations using the time and frequency resources of the LTE cell. The unicast and the MBMS transmission operations are different, and therefore they are separated in a time division fashion as regular subframes and MBMS single frequency network (MBSFN) subframes. Thus, in the downlink (DL), the unicast data is not transmitted on any of the MBSFN subframes, and the MBMS service is not transmitted on any of the regular subframes.
In LTE R9, the MBMS system has no feedback information mechanisms provided or facilitated in order for the MBMS operator to obtain the actual MBMS service reception status and the service subscription status from MBMS-interested WTRUs. There is no provisioning of any uplink (UL) channels, UL MBMS messages, MBMS information elements (IEs) or MBMS signals to allow an MBMS WTRU to communicate with the MBMS service provider.
In LTE Release 10 (R10), MBMS feedback and reporting mechanisms are needed for the service provider to gather the information on what the MBMS-interested WTRUs and users' reception intentions are with respect to the general, and/or a set of, particular MBMS service broadcasts as well as what the MBMS services are that the WTRU/user is receiving at the time.